Standard cell back bias architecture

ABSTRACT

An apparatus including, in one embodiment, a CMOS device cell including at least first and second CMOS transistors having first and second CMOS transistor doped regions in first and second doped wells, respectively, wherein each of the first and second CMOS transistor doped regions is configured to be biased with a corresponding one of a power supply potential and a ground potential. Such an embodiment also includes a tap cell having first and second tap cell doped regions in the first and second doped wells, respectively, wherein each of the first and second tap cell doped regions is configured to be biased with a different potential relative to the power supply and ground potential.

RELATED APPLICATION

The present application is related to and claims the benefit of thepriority date of U.S. Provisional Patent Application No. 60/500,121,entitled “STANDARD CELL BACK BIAS ARCHITECTURE,” and filed Sep. 4, 2003.

BACKGROUND

Advanced complex semiconductor device design and manufacturing hasmatured to a high level of quality mandated by the complexity of processsteps, device circuit density, and the device minimum feature size.Consequently, many design considerations must be considered in thedesign of advanced complex semiconductor devices, including powerdissipation, timing performance, and leakage power, among others. Inresponse, layout, electrical simulation, and many other relatedactivities have been integrated into full-fledged electronic devicedesign systems. Such electronic design systems enable integrated circuit(IC) designers to fabricate complex structures within a computerizedvirtual environment, wherein complex three dimensional cells may beconstructed, electrically simulated, and matched against manufacturingprocess capabilities.

However, challenges still exist in designing and maintaining performanceof devices, particularly as device dimensions continue to decrease. Forexample, electrical performance degradation can occur due to theincreased density of interconnects and logical devices. To assist in thedevelopment of such devices, the layout of developing designs cancomprise myriad basic or standard cell-structures that the IC designercan utilize in an electronic design layout system. The myriad standarddevice cells can include generally employed or frequently used cellscomprised of different configurations of field effect transistors(FETS), conductive interconnect configurations, and a plurality of otherstructures well known by one skilled in the art.

One of the major challenges faced during the development of new designsis the reduction of standby leakage power. Standby leakage power can beassociated with any electrical leakage that may occur while an FET orother cell component is not electrically activated. The standbyelectrical leakage can contribute to degradation in device performance.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale. In fact, the dimensions of the variousfeatures may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a block diagram of at least a portion of one embodiment of asystem for providing an energy efficient cell architecture according toaspects of the present disclosure.

FIG. 2 is a flow-chart diagram of at least a portion of a methodaccording to aspects of the present disclosure.

FIG. 3 a is a layout view of at least a portion of one embodiment of amodified standard tap cell construction according to aspects of thepresent disclosure.

FIG. 3 b is a layout view of at least a portion of one embodiment of amodified standard tap cell construction with interconnect attachmentaccording to aspects of the present disclosure.

FIG. 3 c is a perspective view of at least a portion of one embodimentof a modified standard tap cell construction with interconnectattachment according to aspects of the present disclosure.

FIG. 4 a is a layout view of at least a portion of one embodiment of anintegrated circuit design with inverters and tap cell according toaspects of the present disclosure.

FIG. 4 b is a layout view of at least a portion of one embodiment of anintegrated circuit design with inverters, tap cell, and bias voltageinterconnects according to aspects of the present disclosure.

FIG. 4 c is a perspective view of at least a portion of one embodimentof an integrated circuit design with inverters, tap cell, and biasvoltage interconnects incorporating the constructed according to aspectsof the present disclosure.

FIG. 5 is a layout view of at least a portion of one embodiment of anintegrated circuit design with multiple tap cells and well back biasincorporating other logic devices according to aspects of the presentdisclosure.

FIG. 6 is a circuit diagram of at least a portion of a driving circuitfor providing V_(BB) and V_(pp) voltages to a counter-doped tap cell.

FIG. 7 is a perspective view of at least a portion of an embodiment ofan apparatus in an intermediate stage of manufacture according toaspects of the present disclosure.

FIG. 8 is a perspective view of the apparatus shown in FIG. 7 in asubsequent stage of manufacture according to aspects of the presentdisclosure.

FIG. 9 is a perspective view of the apparatus shown in FIG. 8 in asubsequent stage of manufacture according to aspects of the presentdisclosure.

FIG. 10 is a perspective view of the apparatus shown in FIG. 9 in asubsequent stage of manufacture according to aspects of the presentdisclosure.

FIG. 11 is a perspective view of another embodiment of the apparatusshown in FIG. 10 according to aspects of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the disclosure. Specific examples of components and arrangements aredescribed below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.Moreover, the formation of a first feature over or on a second featurein the description that follows may include embodiments in which thefirst and second features are formed in direct contact, and may alsoinclude embodiments in which additional features may be formedinterposing the first and second features, such that the first andsecond features may not be in direct contact.

Referring to FIG. 1, illustrated is a block diagram of at least aportion of one embodiment of a system 100 describing two componentswhich may be employed in the establishment of a high energy efficient ICcell structure according to aspects of the present invention. The system100, or at least the illustrated portion thereof, includes an electronicintegrated circuit (IC) design component 102 and a leakage power controlIC architecture component 104. The system 100 may further include aplurality of device structures which may be utilized to achieve a highlyenergy efficient IC cell structure.

The electronic IC design component 102 includes a plurality ofelectronic software design tools that can be coupled to variousdatabases, such as those of a semiconductor foundry and/or one or morecustomers of the foundry. For example, the electronic IC designcomponent 102 may include a plurality of device libraries which can beaccessed through a graphical user interface, whereby cells fromindividual device libraries may be placed within an IC design layout.The electronic IC design component 102 may be interconnected to manyother entities across a network. The entities can include and are notlimited to customers, servers, wireless communication devices,terminals, and a plurality of other networked entities. The network canencompass a virtual fab wherein the electronic IC design component 102,manufacturing operations, and other entities mutually share information,communicate, and interact across the network.

The leakage power control IC architecture component 104 may provideunique design techniques and configurations to the electronic integratedcircuit design component 102. The architecture component 104 can providean IC cell design (and/or plurality thereof) that can significantlyreduce the leakage power during device standby and active states. Theelements which comprise the IC can be continuously powered by externalsources (referred to as “static states”), or randomly fired according tospecified operations (referred to as “active states”). An example of anactive state element is an FET. In standby mode, many of the FETs of aparticular device or apparatus may not be active, although power leakagecan still occur.

The architecture component 104 may be employed to provide a back biasfor one or more FETs. For example, the architecture component 104 maycomprise one or more taps to a well corresponding to one or more FETs,and may also include electrically doped regions wherein an electricalconnection may be created to the well containing a plurality of NMOSand/or PMOS devices. In order to implement well voltage biasing, thewell can have a floating potential with respect to the substrate andother electrically grounded NMOS and/or PMOS devices. This can allow forvoltage biasing of a plurality of cells, which can help to providecontrol or reduction of leakage current. Well voltage biasing canfurther provide control of the threshold voltage of the FETs, metaloxide semiconductor FETs (MOSFETs), and/or other devices formed in/on asubstrate.

Referring to FIG. 2, illustrated is a flow-chart diagram of at least aportion of one embodiment of a method 200 of providing an energyefficient cell architecture of the component 104. The method 200 canbegin at a step 202 in which an electronic integrated circuit (IC)design system is provided, initiated, accessed, etc. The electronic ICdesign system may include a plurality of computing devices and softwaresystems that allow for the graphical manipulation of IC componentrepresentations. The IC component representations can include FETs,capacitors, amplifiers, logical operators, resistors, conductinginterconnects, doped regions, and cells constructed of many components,among other possible representations. The electronic IC design systemmay include a plurality of tools for electrical device simulation andmodeling. For example, a simulation program with IC emphasis (e.g.,SPICE) and/or other analytical tools may be incorporated in theelectronic IC design system. The electronic IC design system may becoupled to a plurality of libraries, such as at a step 204 or anotherstep, if not already so coupled. The libraries may comprise ICsub-component layouts, which may be employed for various portions of theoverall design.

Thus, in one embodiment, at step 204, sub-component layouts including aplurality of commonly used or standard IC cell design libraries may beprovided. The standard IC cell design libraries may include a pluralityof semiconductor IC device design cells, such as DRAM, EPROM, EEPROM,SDRAM, and/or other logical devices. The standard IC cell designlibraries may further include cells of analog components, such ascapacitors, inductors, resistors, and/or other components.

At a step 206, new IC cell libraries may be added to the standard ICdesign library. New IC cell libraries may additionally or alternativelybe fabricated by modifying the existing standard IC cell designlibraries. For example, in one embodiment, a tap cell may be created bythe modification of the doped regions of a standard FET or other cell,among other possible modifications. As in embodiments described below orotherwise within the scope of the present disclosure, such tap cells mayprovide well biasing to reduce current leakage and/or tune thresholdvoltage of FET and other cells associated therewith.

For example, a tap cell may comprise one or more doped wells in whichone or more thin oxide or diffusion regions having a greater dopantconcentration is formed. Each such thin oxide or diffusion region mayhereafter be referred to herein as in an “OD” or an “OD region.” In oneembodiment, a tap cell may comprise an N well and a P well, wherein theN well may include an N+ OD and the P well may comprise a P+ OD. The Nwell may additionally or alternatively comprise a P+ OD, and the P wellmay additionally or alternatively comprise an N+ OD. The implantation ofany OD within the scope of the present disclosure may be carried out byion beam implantation, plasma source ion implantation, and/or otherconventional or future-developed processes.

Such tap cells may have interconnects for connecting one or more ODregions with the an external bias voltage source, such that the wells ofassociated PMOS and NMOS devices may be back biased. In someembodiments, such a tap cell may be employed to reduce power leakage inone or more semiconductor devices.

At a step 208, the tap cells and other cells may be laid out in an ICdesign, including in any vertical and/or horizontal position, and can becoupled to a myriad of IC cells. The tap cells may be arranged within anIC design layout prior to, after, or concurrently with the layout ofother cells. The tap cells may be placed at random or specific intervalspacing relative to each other and other types of cells, wherein powerleakage reduction and control may be optimized by the quantity andpositioning of the tap cells. The interval spacing of the tap cells maybe based on the geometric dimensions of associated FETs and otherdevices, such that as geometries continue to shrink the frequency andspacing of tap cells may increase or decrease as desired. The tap cellsmay also have a bias voltage source and/or controller that is separatefrom the voltage source and/or controller of the associated devices. Thevoltage source and/or controller for the tap cells may be located localor remote relative to the associated devices, possibly on a separate dieor chip. Each tap cell may have separate voltage sources, or all tapcells may be controlled by a single voltage source. Clusters of tapcells within an IC may each have a shared voltage, such that eachcluster of tap cells in an IC may be connected to a correspondingvoltage source and/or controller.

Referring to FIG. 3 a, illustrated is a layout view of at least aportion of one embodiment of a tap cell 300 constructed according toaspects of the present disclosure. The tap cell 300 includes an N well(“NW”) 302 and a P well (“PW”) 304. The NW 302 and/or the PW 304 may beintegral to or otherwise contact other wells employed to formneighboring FETs and/or other devices, including standard cells of suchdevices (hereafter collectively referred to as “associated cells”). TheNW 302 and PW 304, including portions thereof that may be employed toform associated cells, may be enclosed by a deep NW (“DNW”), such as inembodiments in which the substrate in which the tap cell 300 is formedis a P doped substrate. The NW 302 may comprise an n+ doped OD (“N+ OD”)306 and a p+ doped OD (“P+ OD”) 310. The P-well 304 may comprise a P+ OD308 and an N+ OD 312. The NW 302 and the PW 304 may be formed adjacentone another, separated by a portion of the substrate in which they areformed, or separated by an isolation structure 322, such as localoxidation or shallow trench isolation, if desired.

Electrical connection to the NW 302 and the PW 304 may be accomplishedthrough the N+ OD 306 and the P+ OD 308. For example, contact to the N+OD 306 and the P+ OD 308 may be accomplished by contacts, vias,interconnects, and/or other conductive elements. Such conductiveelements may comprise one or more conductive layers, possibly includinga refractory barrier material lining and a bulk conductive materialfiller. For example, the illustrated tap cell 300 embodiment employscontacts 320 extending between elements of a first metal layer and theN+ OD 306, the P+ OD 308, the P+ OD 310, and the N+ OD 312. The firstmetal layer may be the first metal layer formed in an IC interconnectstructure formed over the tap cell 300 and associated cells. In theillustrated embodiment, the first metal layer includes an N+ ODinterconnect 314, a P+ OD interconnect 315, a ground interconnect 316,and a power interconnect 318, although additional or alternativeinterconnects may also be formed in the first metal layer, andadditional or alternative metal layers or components may be employed toconnect the NW 302 and the PW 304 to one or more bias voltage sources.

Referring to FIG. 3 b, illustrated is a layout view of the tap cell 300shown in FIG. 3 a in a subsequent stage of manufacture in which the tapcell 300 includes and/or is interconnected by conductive overdrive tapsV_(BB) and V_(pp) or other bias voltage interconnects 326, 328. Theinterconnects 326, 328 may be part of a second metal layer or one ormore higher level metal layers in an interconnect structure. The N+ OD306 and the P+ OD 308 of the tap cell 300 may be electrically connectedto the interconnects 326, 328, respectively, by one or more contacts320. The interconnects 326, 328 may thus connect the N+ OD 306 and theP+ OD 308 to one or more bias voltage power supplies on the substrate,chip or die and/or one or more external power supplies.

Referring to FIG. 3 c, illustrated is a perspective view of at least aportion of one embodiment of the tap cell 300 shown in FIG. 3 b, hereindesignated by the reference numeral 350. The tap cell 350 issubstantially similar to the tap cell 300, although the tap cell 350does not include the isolation structure 322 shown in FIGS. 3 a and 3 b.

The perspective view of the tap cell 350 illustrates the multiple layersthat may be fabricated to form a tap cell according to aspects of thepresent disclosure. For example, in the illustrated embodiment, the tapcell 350 includes a dielectric layer 330 that is deposited or otherwiselocated on or over the N+ OD 306, the P+ OD 308, the P+ OD 310, and theN+ OD 312. The dielectric layer 330 may isolate the N+ OD interconnect314, the P+ OD interconnect 315, the ground interconnect 316, and thepower interconnect 318. The interconnects 314-316, 318 may comprise oneor more refractory metal barrier layers and one or more bulk metallayers. The barrier layers may comprise Ti, TiN, Ta, TaN, TaW, TiW,and/or other materials, and the bulk layers may comprise Cu, Al, and/orother materials. In one embodiment, one or more of the interconnects314-316, 318 and/or the interconnects 326, 328 comprises highlyconductive nano-materials such as carbon nano-tubes, fullerenes, and/orother nano-material, including dopant-implantable nano-material.

Referring to FIG. 4 a, illustrated is a layout view of at least aportion of one embodiment of an apparatus 400 according to aspects ofthe present disclosure. The apparatus 400 is one environment in whichthe tap cell 300 shown in FIGS. 3 a and 3 b and/or the tap cell 350shown in FIG. 3 c may be implemented. In the illustrated embodiment, theapparatus 400 is or composes a portion of a block of associated cells(“cell block”) which includes the tap cell 300 shown in FIGS. 3 a and 3b, an inverter cell 401 a, and a “NAND” cell 401 b. Of course, theapparatus 400 may include associated cells other than and/or or inaddition to those shown in FIG. 4 a. The cell block 400 may beelectrically isolated from other cell blocks by the incorporation of theDNW 324, which may in some embodiments be a deep P well (“DPW”). Thecell block 400 may also or alternatively be isolated from surroundingcell blocks by an outer N doped or P doped ring structure 408.

The inverter and NAND cells 401 a, 401 b may each comprise a pluralityof CMOS transistors formed in corresponding portions of the NW 302 andthe PW 304. The tap cell 300 in the block cell 400 can provide inverter-and/or NAND-cell body potential through back bias to the NW 302 and thePW 304, which can provide a reduction of leakage power of the inverterand NAND cells 401 a, 401 b, and can provide control of IC timingperformance. The PMOS and NMOS devices of the inverter and NAND cells401 a, 401 b may be interconnected by gates 402 and conductiveinterconnects 404. The gates 402 may comprise one or more materiallayers, possibly including a layer of HfO₂ or other high-k materialinterposing layers of ultra-thin, salicided SiO₂ and polysilicon. In oneembodiment, one or more of the gates 402 comprises conductivenano-materials, such as carbon nano-tubes, fullerenes, and/or otherdopant implantable nano-materials.

The cell block 400 with the tap cell 300 (and/or 350) may havewell-biasing voltages of predetermined values at any time upon theapplication of power to an IC. Alternatively, the well-biasing voltagemay be dynamically set based on various operating conditions. Forexample, if the IC is in a sleep mode for power conservation, a signalmay be sent to the tap cell 300 to activate deep back biases to the N+OD 306 and the P+ OD 308, which can result in a significant reduction instandby current leakage of the associated cells. The well-biasingvoltages applied to the N+ OD 306 and the P+ OD 308 can also be set to amyriad of values at different locations within an IC. Therefore, in thecase of a central processing unit which can have many different types oflogical cells, each IC component or cluster of components may havedifferent back bias settings corresponding to different tap cells 300,and which can be simultaneously or sequentially switched to differentvalues corresponding to different modes of operation, possiblyoptimizing the reduction of leakage power. Moreover, the location of theone or more tap cells 300 within each cell block 400 is variable. Forexample, the location may be altered to optimize layout/spacing, such asto maximize cell density while minimizing the drop in back-biaspotential that may occur over an extended distance.

Referring to FIG. 4 b, illustrated is a layout view of the block cell400 shown in FIG. 4 a with the addition of conductive overdrive tapsV_(BB) and V_(pp) or other interconnects 326, 328. The interconnects326, 328 may be interconnected to a cluster of tap cells 300 or to anindividual tap cell 300, wherein pre-selected values for the back biascan be set. The interconnects 326, 328 may be connected to one or moreseparate power supplies other than the power supply employed to powerthe inverter and NAND cells 401 a, 401 b and/or other associated cells.

Referring to FIG. 4 c, illustrated is a perspective view of at least aportion of cell block 400 shown in FIG. 4 b. The ground interconnect(e.g., V_(SS)) 318 and power interconnect (e.g., V_(DD)) 316 connect tothe N+ OD 312 and the P+ OD 310, respectively, such as through one ormore vias 320 or other interconnecting members. A dielectric layer 330may be formed below the ground interconnect 318 and power interconnect316.

Those skilled in the art will recognize that aspects of the presentdisclosure are not limited to the tap cell 300 and/or 350 describedabove. For example, in addition to the embodiments illustrated herein,tap cells formed according to aspects of the present disclosure may beemployed to interconnect myriad numbers and types of featuresincorporated in integrated circuits and other micro-electronic devices.

Referring to FIG. 5, illustrated is a layout view of at least a portionof one embodiment of an integrated circuit 500 comprising a logic array502 according to aspects of the present disclosure. The logic array 502includes tap cells 510 formed integral to an array of associated cellblocks 530, wherein each cell block 530 may comprise a number ofinverter cells, NAND cells, and/or other logic devices. Each of the tapcells 510 may be substantially similar to one or more of the tap cells300, 350 described above. The logic array 502 may comprise a number ofcell blocks 520, one or more of which may be substantially similar tothe cell block 400 described above, although the cell blocks 520 maycomprise a larger number of inverter cells, NAND cells, and/or otherCMOS devices than the two cells depicted in FIGS. 4 a-4 c, such thatlarge arrays of CMOS devices may be back biased by the plurality of tapcells 510.

Referring now to FIG. 6, illustrated is a circuit diagram of at least aportion of one embodiment of a driving circuit 600 which may be employedto provide V_(BB) and V_(pp) voltages to a tap cell according to aspectsof the present disclosure. The driving circuit 600 may be fabricated onthe same chip or die and proximate a plurality of tap cells along with alogic array. The driving circuit 600 may alternatively be located offthe chip or die, possibly being located on another chip. The drivingcircuit 600 may provide continuous, pulsed, and/or periodic V_(BB) andV_(pp) voltages to tap cells. The V_(BB) and V_(pp) voltages produced bythe driving circuit 600 may be controlled through a feed-back loopwherein dynamic V_(BB) and V_(pp) voltages may be applied according toexternal conditions from sensory devices. For example, the feed-backsystem may include a thermocouple wherein the dynamic V_(BB) and V_(pp)voltages applied to one or more tap cells may be dependent upon thetemperature sensed by the thermocouple.

Referring to FIG. 7, illustrated is a perspective view of at least aportion of one embodiment of an apparatus 700 in an intermediate stageof manufacture according to aspects of the present disclosure. Theapparatus 700 includes a substrate 705 which may substantially compriseP doped silicon. In other embodiments, the substrate 705 may notsubstantially comprise P doped silicon, but may comprise a number ofdeep P wells, or may comprise silicon other than P doped silicon. Forthe sake of simplicity, the following discussion assumes that thesubstrate 705 substantially comprises P doped silicon. However, thoseskilled in the art will recognize that the description that follows isapplicable and/or readily adaptable to embodiments of the apparatus 700in which the substrate 705 does not substantially comprise P dopedsilicon but are still within the scope of the present disclosure.

The apparatus 700 may comprise a deep N doped well (“DNW”) 710 formed byconventional or future-developed processes. The DNW 710 may be employedto physically and/or electrically isolate an N doped well (“NW”) 715 anda P doped well (“PW”) 720 from nearby elements. A doped ring structuremay additionally or alternatively be employed for such isolation.

The apparatus 700 may include one or more devices associated with one ormore tap cells, such that the tap cells may back bias one or more of theassociated devices. Accordingly, the substrate 705 may include aplurality of tap cell regions in each of which such a tap cell may beformed according to aspects of the present disclosure. Only one such tapcell region 725 is depicted in the illustrated embodiment, although thesubstrate 705 may include any number of tap cell regions 725 as maycorrespond to the number of tap cells included in the apparatus 700.

The substrate 705 may also include a number of associated deviceregions, such as associated device regions 730 a, 730 b. Of course, manyembodiments will include many more associated device regions than thetwo regions 730 a, 730 b shown in the illustrated embodiment. Thus, anyreference to the associated device regions 730 a, 730 b herein isapplicable or readily adaptable to the other associated device regionsnot shown in FIG. 7. Also, although depicted as being at or proximate anend or perimeter of a block or cluster of associated device regions 730a, 730 b, or otherwise proximate the perimeter of the block ofassociated device regions 730 a, 730 b, the tap cell region 725 may alsobe positioned at other locations within a particular cluster ofassociated device regions 730 a, 730 b, such as a position that isproximate a central region of the block of associated device regions 730a, 730 b.

An N+ doped region (“N+ OD”) 735 may be formed in the NW 715 and withinthe tap cell region 725. The N+ OD 735 may comprise a thin oxide ordiffusion formed by ion implantation and/or other conventional and/orfuture-developed processes. In one embodiment, the N+ OD 735 may beformed by processes similar to those employed to form N+ typesource/drain regions of CMOS transistors and, as such, may besubstantially similar in composition and/or geometry to an N+ typesource/drain region. In fact, in one embodiment, the N+ OD 735 may beformed simultaneously with the formation of such N+ type source/drainregions.

A P+ doped region (“P+ OD”) 740 may be formed in the PW 720 and withinthe tap cell region 725. The P+ OD 740 may also comprise a thin oxide ordiffusion formed by ion implantation and/or other conventional and/orfuture-developed processes. The P+ OD 740 may be formed by processessimilar to those employed to form P+ type source/drain regions of CMOStransistors and, as such, may be substantially similar in compositionand/or geometry to a P+ type source/drain region. In fact, in oneembodiment, the P+ OD 740 may be formed simultaneously with theformation of such P+ type source/drain regions.

The apparatus 700 may also include an additional P+ OD 745 formed in theNW 715 and extending at least partially into the tap cell region 725although, as in the illustrated embodiment, the P+ OD 745 may alsoextend completely through the tap cell region 725. As also shown in theillustrated embodiment, the P+ OD 745 may extend from the tap cellregion 725 and into one or more or each of the associated device regions730 a, 730 b. In one embodiment, however, the P+ OD region 745 may notextend into the tap cell region 725, or may be substantially confined toextending between adjacent ones of the associated device regions 730 a,730 b. The P+ OD 745 may also include source/drain extensions 745 a, 745b each extending towards a central portion of a corresponding one of theassociated devices regions 730 a, 730 b, possibly in a direction that issubstantially perpendicular to the remaining or main portion of the P+OD 745, although also remaining substantially confined within the NW715.

The apparatus 700 may also include an additional N+ OD 750 formed in thePW 720 and extending at least partially into the tap cell region 725although, as in the illustrated embodiment, the N+ OD 750 may alsoextend completely through the tap cell region 725. The N+ OD 750 mayextend from the tap cell region 725 and into one or more or each of theassociated device regions 730 a, 730 b. In one embodiment, however, theN+ OD region 750 may not extend into the tap cell region 725, or may besubstantially confined to extending between adjacent ones of theassociated device regions 730 a, 730 b. The N+ OD 750 may also includesource/drain extensions 750 a, 750 b each extending towards a centralportion of a corresponding one of the associated devices regions 730 a,730 b, possibly in a direction that is substantially perpendicular tothe remaining or main portion of the N+ OD 750, although substantiallyconfined within the PW 720.

In some embodiments, the N+ OD 735 and the P+ OD 740, possibly inconjunction with proximate regions of the NW 715 and the PW 720,substantially compose a tap cell, which may generally conform to and/orbe indicated by the tap cell region 725. Thus, the following discussionrelative to the tap cell region 725 is applicable or readily adaptableto a tap cell comprising the N+ OD 735, the P+ OD 740, and regions ofthe NW 715 and the PW 720 that are substantially within the imaginaryborder of the tap cell region 725 indicated by dashed lines in FIG. 7.In other embodiments, such a tap cell may comprise additionalcomponents, elements, or features, such as a portion of the DNW 710within the tap cell region 725, portions of the P+ OD 745 and the N+ OD750 within the tap cell region 725, and/or other items that may beformed over the tap cell regions, such as gate electrodes,interconnects, and other conductive members, as well as portions ofinsulating or dielectric layers within the tap cell region 725.

Additional P+ OD regions 755 a, 755 b may be formed in the NW 715, eachwithin a corresponding one the associated device regions 730 a, 730 b.The P+ OD regions 755 a, 755 b may be source/drain regions and, thus,may be laterally offset from the main portion of the P+ OD 745 and theextensions 745 a, 745 b thereof. Similarly, additional N+ OD regions 760a, 760 b may be formed in the PW 715, each within a corresponding onethe associated device regions 730 a, 730 b. The N+ OD regions 760 a, 760b may also be source/drain regions and, thus, may be laterally offsetfrom the main portion of the N+ OD 750 and the extensions 750 a, 750 bthereof.

Referring to FIG. 8, illustrated is a perspective view of the apparatus700 shown in FIG. 7 in a subsequent stage of manufacture in which a gatefabrication process has been performed to form gate electrodes 810 a,810 b in each of the associated device regions 730 a, 730 b,respectively. The gate electrodes 810 a, 810 b may be formed byconventional or future-developed processes, such that each of the gateelectrodes 810 a, 810 b may comprise one or more layers of dielectricmaterial (e.g., gate oxide layers) collectively interposing one or morelayers of polysilicon or other conductive materials. Moreover, althoughdepicted herein as being formed after the OD regions 745, 750, 755 a,755 b, 760 a, 760 b are formed, those skilled in the art will recognizethat the gate electrodes 810 a, 810 b may be partially or completelyformed prior to forming the OD regions, such that in some embodimentsself-alignment principles may be employed.

Each of the illustrated gate electrodes 810 a, 810 b may substantiallyspan the lateral separation between neighboring pairs of the OD regions745, 750, 755 a, 755 b, 760 a, 760 b. For example, the gate electrode810 a includes a portion 815 a substantially spanning the lateral offsetbetween the P+ OD extension 745 a and the P+ OD 755 a in a directionthat is substantially parallel to the longitudinal axis of the P+ OD745, and also includes a portion 815 b substantially spanning thelateral offset between the N+ OD extension 750 a and the N+ OD 760 a ina direction that is substantially parallel to the longitudinal axis ofthe N+ OD 750. Each of the portions 815 a, 815 b may extend laterallyaway from a central portion of the associated device region 730 a to orbeyond an outer edge of the P+ OD 755 a and the N+ OD 760 a,respectively. The gate electrode 810 a may also include an extension 815c extending away from a central portion of the associated device region730 a to or beyond an edge of the P+ OD extension 745 a that is oppositethe gate electrode portion 810 a, possibly in a direction that issubstantially parallel to the longitudinal axis of the P+ OD 745 and/orthe N+ OD 750. The gate electrode 810 b may be substantially similar inshape and/or other configuration aspects to the above-described aspectsof the gate electrode 810 a.

The gate electrodes 810 a, 810 b described above may have shapes,patterns, profiles, and/or other aspects that differ from those shown inFIG. 8. For example, the illustrated gate electrodes 810 a, 810 b may beemployed when the device being formed in each of the associated deviceregions 730 a, 730 b is an inverter device. However, other shapes orpatterns of the gate electrodes 810 a, 810 b, as well as the number ofgate electrodes in each associated device region 730 a, 730 b, may bealtered if other types of devices are being formed in the associateddevice regions 730 a, 730 b.

Referring to FIG. 9, illustrated is a perspective view of the apparatus700 shown in FIG. 8 in a subsequent stage of manufacture in which aelements of a first metal layer and corresponding contacts have beenformed. The first metal layer may be substantially similar incomposition and manufacture to a metal layer employed in an interconnectstructure of an integrated circuit device, and in some embodiments isactually defined from the first metal layer in such an interconnectstructure. However, in other embodiments, one or more or each of theelements described below as being defined in a first metal layer of aninterconnect structure may also or alternatively be defined in or fromanother metal layer of an interconnect structure, such as a third metallayer therein. For the sake of clarity, however, the followingdiscussion assumes that the first metal layer of the associated deviceinterconnect structure is employed as the first conductive layeremployed in the interconnection of the one or more tap cells formed inthe apparatus 700, although such assumption is not limiting to the scopeof the present disclosure.

In one embodiment, the first metal layer may be formed by forming one ormore substantially planar pre-level and/or interlevel dielectric layersover the gate electrodes 810 a, 810 b and the substrate 705, includingover the OD regions 745, 750, 755 a, 755 b, 760 a, 760 b, andsubsequently forming conductive members in and/or on the one or moredielectric layers. The dielectric layers may comprise silicon dioxide,SILK (a product of Dow Chemical of Michigan), BLACK DIAMOND (a productof Applied Materials of Santa Clara, Calif.), and/or other insulatingmaterials, and the conductive members may comprise one or more layers ofconductive and/or refractive materials. For the sake of clarity, the oneor more dielectric layers interposing the first metal layer conductivemembers and the substrate 705 or other underlying features is not shownin FIG. 9.

One of the conductive members formed in the first metal layer in theapparatus 700 may be an interconnect 910 that may be connected to the P+OD 745 at various locations by vias, contacts, or other interconnects(hereafter collectively referred to as interconnects), several of whichare designated by the reference numeral 920 in FIG. 9. The interconnect910 may extend over one or more or each of the tap cell region 725 andthe associated device regions 730 a, 730 b, possibly in a direction thatis substantially parallel to the P+ OD 745. The interconnect 910 may beultimately connected to a power supply that is employed, at least inpart, in driving the associated devices formed in the associated deviceregions 730 a, 730 b, such as by providing a power supply voltage orpotential. Thus, the interconnect 910 may be a V_(DD) interconnect.Moreover, the P+ OD 745 may be a source OD for associated PMOS devicesformed in the associated device regions 730 a, 730 b.

Another of the conductive members formed in the first metal layer in theapparatus 700 may be an interconnect 930 that may be connected to the N+OD 750 at various locations by interconnects 920. The interconnect 930may extend over one or more or each of the tap cell region 725 and theassociated device regions 730 a, 730 b, possibly in a direction that issubstantially parallel to the P+ OD 745, the N+ OD 750, and/or theinterconnect 910. The interconnect 930 may be ultimately connected to aground conductor or other ground potential source that is employed, atleast in part, in driving the associated devices formed in theassociated device regions 730 a, 730 b. Thus, the interconnect 920 maybe a V_(SS) interconnect. Moreover, the N+ OD 750 may be a source OD forassociated NMOS devices formed in the associated device regions 730 a,730 b.

The first metal layer in which the interconnects 910, 930 are definedmay also include an interconnect 940 that may be connected to the N+ OD735 by an interconnect 920, as well as an interconnect 950 that may beconnected to the P+ OD 740 by an interconnect 920. The interconnects940, 950 may extend in substantially opposite directions, possibly indirections that are substantially parallel to the P+ OD 745, the N+ OD750, and/or the interconnects 910, 930.

The apparatus 700 may also include various interconnects 955 connectedto the gate electrodes 810 a, 810 b or OD regions 745 a, 745 b, 750 a,750 b, 755 a, 755 b, 760 a, 760 b. These interconnects 955 may beemployed for interconnecting devices formed in the associated deviceregions 730 a, 730 b, such as may be necessary to perform desired logicand/or other CMOS device functions. However, because use of the tap cellformed in the tap cell region 725 is applicable or readily adaptablewith a variety of CMOS device configurations, the furtherinterconnection of the associated devices in the associated deviceregions 730 a, 730 b through the interconnects 955, whether directly orindirectly, will not be further discussed herein. Nonetheless, examplesof such interconnection of devices formed in the associated deviceregions 730 a, 730 b are provided in the discussion above.

Referring to FIG. 10, illustrated is a perspective view of the apparatus700 shown in FIG. 9 in a subsequent stage of manufacture in which aelements of a second metal layer and corresponding contacts have beenformed. The second metal layer may be substantially similar incomposition and manufacture to a metal layer employed in an interconnectstructure of an integrated circuit device, and in some embodiments isactually defined from the second metal layer in such an interconnectstructure. However, in other embodiments, one or more or each of theelements described below as being defined in a second metal layer of aninterconnect structure may also or alternatively be defined in anothermetal layer of an interconnect structure, such as a fourth metal layertherein. For the sake of clarity, however, the following discussionassumes the second metal layer of the associated device interconnectstructure is employed as the second conductive layer employed in theinterconnection of the one or more tap cells being formed in theapparatus 700.

The second metal layer may be formed by forming one or moresubstantially planar interlevel dielectric layers over the interconnects910, 930, 940, 950, 955 and one or more previously formed pre-leveland/or interlevel dielectric layers, and subsequently forming conductivemembers in and/or on the one or more dielectric layers. The dielectriclayers may be substantially similar in composition and manufacture tothe previously formed pre-level and/or interlevel dielectric layers, andthe conductive members may comprise one or more layers of conductiveand/or refractive materials. For the sake of clarity, the one or moredielectric layers interposing the second metal layer conductive membersand the interconnects 910, 930, 940, 950, 955 or other underlyingfeatures is not shown in FIG. 10.

One of the conductive members formed in the second metal layer in theapparatus 700 may be an interconnect 960 that may be connected to theinterconnect 940 by an interconnect 920. The interconnect 960 may extendover the tap cell region 725, possibly in a direction that issubstantially perpendicular to the longitudinal axis of the P+ OD 745,the N+ OD 750, and/or the interconnects 910, 930. The interconnect 960may be ultimately connected to a power supply that is employed, at leastin part, in adjusting the back bias of the NW 715, including theportions of the NW 715 in which at least portions of associated PMOSdevices formed in the associated device regions 730 a, 730 b may beformed. The power supply employed to back-bias the NW 715 may beseparate from the power supply employed in driving devices formed in theassociated device regions 730 a, 730 b, and may not be located on thesame die or chip as the apparatus 700. For example, the NW 715 back-biaspower supply may be ultimately connected to the apparatus 700 by wirebonding, flip-chip bonding, and/or other interconnection means.

The interconnect 960 may be a V_(BB) interconnect. In such embodiments,the V_(BB) potential at which the NW 715 may be biased via theinterconnect 960 may be different than the potential of the power supplyemployed in driving devices formed in the associated device regions 730a, 730 b (V_(DD) in the present discussion) or the ground potentialemployed for such devices (V_(SS) in the present discussion). Forexample, V_(BB) may be greater than or less than V_(DD) in magnitudeand/or amplitude, may be in-phase or out-of-phase relative to V_(DD),and may be applied to the NW 715 concurrently with or at different timesrelative to the application of V_(DD) to devices formed in theassociated devices regions 730 a, 730 b. Moreover, whereas V_(DD) islikely a predetermined potential or signal, V_(BB) may be dynamicallyadjustable or tunable, such that the back bias of the NW 715 may also betunable.

Another conductive member formed in the second metal layer in theapparatus 700 may be an interconnect 965 that may be connected to theinterconnect 950 by an interconnect 920. The interconnect 965 may extendover the tap cell region 725, possibly in a direction that issubstantially perpendicular to the longitudinal axis of the P+ OD 745,the N+ OD 750, and/or the interconnects 910, 930, and/or substantiallyparallel to the interconnect 960. The interconnect 965 may be ultimatelyconnected to a power supply that is employed, at least in part, inadjusting the back-bias of the PW 720, including the portions of the PW720 in which at least portions of associated NMOS devices formed in theassociated device regions 730 a, 730 b may be formed.

The power supply employed to back-bias the PW 720 may be separate fromthe power supply employed in driving devices formed in the associateddevice regions 730 a, 730 b, and may not be located on the same die orchip as the apparatus 700. For example, the PW 720 back-bias powersupply may be ultimately connected to the apparatus 700 by wire bonding,flip-chip bonding, and/or other interconnection means. The PW 720back-bias power supply may also be part of, the same as, or otherwiseassociated with the NW 715 back-bias power supply.

As used herein, the interconnect 965 may be a V_(pp) interconnect. Thatis, the V_(pp) potential at which the PW 720 may be biased may bedifferent than V_(DD) or V_(SS). For example, V_(pp) may be greater thanor less than V_(DD) in magnitude and/or amplitude, may be in-phase orout-of-phase relative to V_(DD), and may be applied to the PW 720concurrently with or at different times relative to the application ofV_(DD) to devices formed in the associated devices regions 730 a, 730 b.Moreover, whereas V_(DD) is likely a predetermined potential or signal,V_(pp) may be dynamically adjustable or tunable, such that the back biasof the PW 720 may also be tunable.

The control of V_(BB) and V_(pp) may be accessed off-chip or throughprogrammable on-chip apparatus, such as one or more charge pumps and oneor more bias voltage regulators. The control of V_(BB) and V_(pp) mayalso be constructed in preset values at power-up from either off-chip oron-chip. In one embodiment, the control of V_(BB) and V_(pp) may beconfigured as high bias voltages during sleep/idle mode(s) for lowleakage power, and be connected to V_(SS) and V_(DD) for active mode.

Aspects of the tap cells described herein may also make forward-biaspossible for performance with more expected leakages. For example, forforward biasing, V_(BB) can be higher than V_(SS), and V_(pp) can belower than V_(DD). Aspects of the present disclosure may also permit aback-bias scheme to be mixed with many threshold voltage (V_(t))technology improvements, which may allow for varying V_(t) within theapparatus 700, such as to provide an extra high V_(t) implant and a lowV_(t) implant in addition to a nominal V_(t) implant for increasinglyaccurate, grained control of timing performance and leakage powercontrol.

Examples of applications in which aspects of the present application maybe employed include setting V_(BB) and V_(pp) to pre-determined valuesstatically at any time or during powering up. V_(BB) and V_(pp) may alsobe dynamically set to pre-determined or other values, such as when achip containing one or more tap cells and associated devices: (1) isdetermined to go into back-bias state or such status change is triggeredby external events; (2) sends a trigger signal to activate the back-biasvoltage controller, or another chip sends such a trigger signal,possibly depending on internal or external events; and/or (3) aback-bias voltage controller sends V_(BB) and V_(pp) to the chip tofulfill the back-bias control. Thus, in addition to the one or moreback-bias power supplies connected ultimately to the NW 715 and the PW720 to bias the NW 715 and PW 720 with different potential levelsrelative to the power supply and ground potential, including where thepotential employed to bias the NW 715 is different than the potentialemployed to bias the PW 720, the back-bias controller apparatus whichmay be employed to achieve such additional voltage potentials to applyto the NW 715 and the PW 720 may also be designed in-chip or off-chip.

Referring to FIG. 11, illustrated is a perspective view of at least aportion of another embodiment of the apparatus 700 shown in FIG. 10,herein designated by the reference numeral 700 a. The apparatus 700 a issubstantially similar to the apparatus 700 shown in FIG. 10. However,while it is discussed above that the apparatus 700 may include tap cellsin addition to the single tap cell formed in the single tap cell region725 shown in FIG. 10, and may also include associated devices inaddition to the devices formed in the associated device regions 730 a,730 b shown in FIG. 10, the apparatus 700 a shown in FIG. 11 depictsmultiple tap cells 725 a each corresponding to devices formed inmultiple associated device regions.

In one embodiment, the multiple tap cells 725 a may each be aligned withothers of the tap cells 725 a. For example, the tap cells 725 a may bepositioned in a grid-like pattern, such as where the lateral sides ofeach tap cell 725 a are substantially aligned with the lateral sides ofat least one other tap cell 725 a, such that the interconnects 960, 965employed to interconnect the tap cells 725 a to each other maysubstantially comprise straight, elongated members extending betweeneach neighboring, connected pair of tap cells 725 a. Consequently, theinterconnects 960, 965 need not require any bends or turns tointerconnect neighboring pairs of tap cells 725 a.

Thus, in one embodiment, apparatus constructed according to aspects ofthe present disclosure may include two or more sets of the interconnects960, 965. However, in some embodiments it may not be possible or desiredto align all of the tap cells included on a chip. Moreover, it may notbe desirable to configure the interconnects 960, 965 to have more thanone substantially elongated segment. That is, it may not be desirable toconfigure the interconnects 960, 965 as having one or more bends, or oneor more perpendicular or otherwise angularly offset segments.

Thus, while not shown in FIG. 11, additional interconnects similar incomposition, manufacture, and function to the interconnects 960, 965 maybe employed in orientations that are laterally offset from theinterconnects 960, 965 in a direction perpendicular to interconnects960, 965. Such additional interconnects for providing a back-biaspotential to tap cells not sufficiently aligned with the tap cells 725 amay have common power supplies and or controllers as those connected tothe tap cells 725 a by the interconnects 960, 965. Alternatively,separate power supplies and/or controllers may be connected to thenon-aligned tap cells by the additional interconnects.

Thus, the present disclosure provides an apparatus including, in oneembodiment, a CMOS device cell including at least first and second CMOStransistors having first and second CMOS transistor doped regions infirst and second doped wells, respectively, wherein each of the firstand second CMOS transistor doped regions is configured to be biased witha corresponding one of a power supply potential and a ground potential.Such an embodiment also includes a tap cell having first and second tapcell doped regions in the first and second doped wells, respectively,wherein each of the first and second tap cell doped regions isconfigured to be biased with a different potential relative to the powersupply and ground potentials.

Another embodiment of an apparatus introduced in the present disclosureincludes a plurality of tap cells each corresponding to associated onesof a plurality of CMOS transistor devices. In such an embodiment, onesof the plurality of CMOS transistor devices are configured to be biasedwith at least one of a power supply potential and a ground potential.Moreover, each of the plurality of tap cells is configured to back-biasassociated ones of the plurality of CMOS transistor devices with one offirst and second potentials that are each a different potential relativeto the power supply and ground potentials. In a related embodiment, onesof the plurality of CMOS transistor devices collectively compose aplurality of CMOS device cells, and the plurality of CMOS device cellscollectively compose a plurality of CMOS device cell blocks eachcomprising a plurality of CMOS device cells associated with acorresponding one of the plurality of tap cells.

The present disclosure also introduces an apparatus including an N welllocated in a substrate, a P well located in the substrate proximate theN well, and a tap cell including an N+ doped region in the N well and aP+ doped region in the P well. A plurality of CMOS device cells includedin the apparatus includes a plurality of CMOS transistor devices eachhaving source/drain regions in a corresponding one of the N well and theP well. Power supply and ground interconnects are configured to connectthe source/drain regions of ones of the plurality of CMOS transistordevices at least indirectly to a corresponding one of a power supply andground, such that the connected source/drain regions may be biased witha corresponding one of a power supply potential and a ground potential.A first back-bias interconnect and a second back-bias interconnect areconfigured to connect the N well and the P well, respectively, at leastindirectly to first and second back-bias sources, such that the N welland the P well may be biased with a first and second back-biaspotential, respectively, that are each a different potential relative tothe power supply and ground potential.

In a related embodiment, the N well is one of a plurality of N wellseach located in the substrate, the P well is one of a plurality of Pwells each located in the substrate, the tap cell is one of a pluralityof tap cells each including an N+ doped region in a corresponding one ofthe plurality of N wells and a P+ doped region in a corresponding one ofthe plurality of P wells, and the plurality of CMOS device cells composea plurality of cell blocks each associated with at least one of theplurality of tap cells.

The present disclosure also provides a method which may be employed, forexample, to form a back-biasing architecture that may be employed withstandard CMOS device cells. In one embodiment, the method includesforming an N well in a substrate, forming a P well in the substrateproximate the N well, and forming a tap cell including an N+ dopedregion in the N well and a P+ doped region in the P well. Such a methodalso includes forming a plurality of CMOS device cells each including aplurality of CMOS transistor devices each having source/drain regions ina corresponding one of the N well and the P well, as well as formingpower supply and ground interconnects configured to at least indirectlyconnect the source/drain regions of ones of the plurality of CMOStransistor devices to a corresponding one of a power supply and groundto bias the connected source/drain regions with a corresponding one of apower supply potential and a ground potential. A first back-biasinterconnect and a second back-bias interconnect may be formed and/orotherwise configured to at least indirectly connect the N well and the Pwell, respectively, to first and second back-bias sources to bias the Nwell and the P well with a first and second back-bias potential,respectively, that are each a different potential relative to the powersupply and ground potential.

The foregoing has outlined features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions andalterations herein without departing from the spirit and scope of thepresent disclosure.

1. An apparatus, comprising: a CMOS device cell including at least firstand second CMOS transistors having first and second CMOS transistordoped regions in first and second doped wells, respectively, whereineach of the first and second CMOS transistor doped regions is configuredto be biased with a corresponding one of a power supply potential and aground potential; and a tap cell having first and second tap cell dopedregions in the first and second doped wells, respectively, wherein eachof the first and second tap cell doped regions is configured to bebiased with a different potential relative to the power supply andground potentials.
 2. The apparatus of claim 1 wherein the first andsecond tap cell doped regions are configured to be biased with differentfirst and second potentials, respectively, that are each a differentpotential relative to the power supply and ground potentials.
 3. Theapparatus of claim 1 wherein the CMOS device cell is a standard librarycell.
 4. The apparatus of claim 3 wherein the tap cell and the CMOSdevice cell have substantially similar shapes and lateral dimensions. 5.The apparatus of claim 1 wherein at least one of magnitude and amplitudeof the different potential is different relative to the power supply andground potentials.
 6. The apparatus of claim 1 wherein at least one ofphase and polarity of the different potential is different relative tothe power supply and ground potentials.
 7. The apparatus of claim 1wherein the first and second tap cell doped regions are configured to bebiased at times in addition to when the power supply potential isbiasing the corresponding one of the first and second CMOS transistordoped regions.
 8. The apparatus of claim 1 wherein: the first and seconddoped wells have opposite dopant types; the first tap cell doped regionhas the same dopant type as the first doped well but a higher dopantconcentration relative to the first doped well; and the second tap celldoped region has the same dopant type as the second doped well but ahigher dopant concentration relative to the second doped well.
 9. Anapparatus, comprising: a plurality of tap cells each corresponding toassociated ones of a plurality of CMOS transistor devices, wherein onesof the plurality of CMOS transistor devices are configured to be biasedwith at least one of a power supply potential and a ground potential,and wherein each of the plurality of tap cells is configured toback-bias associated ones of the plurality of CMOS transistor deviceswith one of first and second potentials that are each a differentpotential relative to the power supply and ground potentials.
 10. Theapparatus of claim 9 wherein ones of the plurality of CMOS transistordevices collectively compose a plurality of CMOS device cells, theplurality of CMOS device cells collectively composing a plurality ofCMOS device cell blocks each comprising a plurality of CMOS device cellsassociated with a corresponding one of the plurality of tap cells. 11.The apparatus of claim 9 wherein each of the plurality of tap cells isconfigured to back bias each of the plurality of CMOS transistor devicesof a corresponding one of the plurality of CMOS device cells of acorresponding one of the plurality of CMOS device cell blocks with acorresponding one of the first and second potentials.
 12. The apparatusof claim 9 wherein at least one of magnitude and amplitude of each ofthe first and second potentials is different relative to the powersupply and ground potentials.
 13. The apparatus of claim 9 wherein atleast one of phase and polarity of each of the first and secondpotentials is different relative to the power supply and groundpotentials.
 14. The apparatus of claim 9 wherein ones of the pluralityof tap cells are configured to back-bias associated ones of theplurality of CMOS transistor devices with one of first and secondpotentials at times in addition to when the power supply potential isapplied to corresponding ones of associated CMOS device cells.
 15. Theapparatus of claim 9 further comprising: a power interconnect connectingones of the plurality of CMOS transistor devices at least indirectly toa power supply potential source; and a ground interconnect connectingones of the plurality of CMOS transistor devices at least indirectly toa ground potential source.
 16. The apparatus of claim 15 furthercomprising: a first back bias interconnect at least indirectlyconnecting ones of the plurality of CMOS transistor devices to a firstpotential source; and a second back bias interconnect at leastindirectly connecting ones of the plurality of CMOS transistor devicesto a second potential source.
 17. The apparatus of claim 16 wherein thepower and ground interconnects are each substantially parallel to afirst lateral direction relative to an underlying substrate and whereinthe first and second back bias interconnects are each substantiallyparallel to a second lateral direction relative to the substrate,wherein the first and second lateral directions are substantiallyperpendicular.
 18. The apparatus of claim 17 further comprising aninterconnect structure including first and second metal layers havingconductive members interconnecting ones of the plurality of CMOStransistor devices to form ones of the plurality of CMOS device cells,wherein the power and ground interconnects are located in the firstmetal layer of the interconnect structure, and wherein the first andsecond back bias interconnects are located in the second metal layer ofthe interconnect structure.
 19. The apparatus of claim 9 wherein each ofthe plurality of tap cells and each of the plurality of CMOS devicecells have footprints of substantially similar shape and orientation.20. An apparatus, comprising: an N well located in a substrate; a P welllocated in the substrate proximate the N well; a tap cell including anN+ doped region in the N well and a P+ doped region in the P well; aplurality of CMOS device cells each including a plurality of CMOStransistor devices each having source/drain regions in a correspondingone of the N well and the P well; power supply and ground interconnectsconfigured to connect the source/drain regions of ones of the pluralityof CMOS transistor devices at least indirectly to a corresponding one ofa power supply and ground to bias the connected source/drain regionswith a corresponding one of a power supply potential and a groundpotential; and a first back-bias interconnect and a second back-biasinterconnect configured to connect the N well and the P well,respectively, at least indirectly to first and second back-bias sourcesto bias the N well and the P well with a first and second back-biaspotential, respectively, that are each a different potential relative tothe power supply and ground potential.
 21. The apparatus of claim 20further comprising an interconnect structure including first and secondmetal layers having a plurality of conductive members interconnectingones of the plurality of CMOS transistor devices to form ones of theplurality of CMOS device cells, wherein the power supply and groundinterconnects each at least partially include one of the plurality ofconductive members in the first metal layer, and wherein the first andsecond back-bias interconnects each at least partially include one ofthe plurality of conductive members in the second metal layer.
 22. Theapparatus of claim 20 wherein the power supply and ground interconnectsare substantially parallel, and wherein the first and second back-biasinterconnects are substantially parallel and each substantiallyperpendicular to the power supply and ground interconnects.
 23. Theapparatus of claim 20 wherein: the N well is one of a plurality of Nwells each located in the substrate; the P well is one of a plurality ofP wells each located in the substrate; the tap cell is one of aplurality of tap cells each including an N+ doped region in acorresponding one of the plurality of N wells and a P+ doped region in acorresponding one of the plurality of P wells; and the plurality of CMOSdevice cells compose a plurality of cell blocks each associated with atleast one of the plurality of tap cells.
 24. The apparatus of claim 23wherein each of the plurality of tap cells is oriented proximate aperimeter of a corresponding one of the plurality of cell blocks. 25.The apparatus of claim 23 wherein each of the plurality of tap cells isoriented in a central portion of a corresponding one of the plurality ofcell blocks.
 26. The apparatus of claim 20 wherein the N well and the Pwell are electrically isolated from the substrate.
 27. The apparatus ofclaim 26 wherein a deep doped well electrically isolates the N well andthe P well from the substrate.
 28. The apparatus of claim 20 furthercomprising an isolation structure interposing the N well and the P wellin the substrate.
 29. A method, comprising: forming an N well in asubstrate; forming a P well in the substrate proximate the N well;forming a tap cell including an N+ doped region in the N well and a P+doped region in the P well; forming a plurality of CMOS device cellseach including a plurality of CMOS transistor devices each havingsource/drain regions in a corresponding one of the N well and the Pwell; forming power supply and ground interconnects configured to atleast indirectly connect the source/drain regions of ones of theplurality of CMOS transistor devices to a corresponding one of a powersupply and ground to bias the connected source/drain regions with acorresponding one of a power supply potential and a ground potential;and forming a first back-bias interconnect and a second back-biasinterconnect configured to at least indirectly connect the N well andthe P well, respectively, to first and second back-bias sources to biasthe N well and the P well with a first and second back-bias potential,respectively, that are each a different potential relative to the powersupply and ground potential.
 30. The method of claim 29 furthercomprising forming an interconnect structure including first and secondmetal layers having a plurality of conductive members interconnectingones of the plurality of CMOS transistor devices to form ones of theplurality of CMOS device cells, wherein the power supply and groundinterconnects each at least partially include one of the plurality ofconductive members in the first metal layer, and wherein the first andsecond back-bias interconnects each at least partially include one ofthe plurality of conductive members in the second metal layer.
 31. Themethod of claim 29 wherein the power supply and ground interconnects aresubstantially parallel, and wherein the first and second back-biasinterconnects are substantially parallel and each substantiallyperpendicular to the power supply and ground interconnects.
 32. Themethod of claim 29 wherein: forming the N well includes forming aplurality of N wells each located in the substrate; forming the P wellincludes forming a plurality of P wells each located in the substrate;forming the tap cell includes forming a plurality of tap cells eachincluding an N+ doped region in a corresponding one of the plurality ofN wells and a P+ doped region in a corresponding one of the plurality ofP wells; and forming the plurality of CMOS device cells includes forminga plurality of cell blocks each associated with at least one of theplurality of tap cells.